At engine oil temperatures above approximately 302°F (150°C) the cooling fan duty cycle will be commanded to high speed.

At transmission oil temperatures above approximately 270°F (132°C) the cooling fan duty cycle will be commanded to high speed.

After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 235°F (113°C) or the A/C pressure is greater than 249 psi (1720 kPa) the cooling fan duty cycle is set to 50%,low speed. If the coolant temperature drops below 230°F (110°C) and the A/C pressure drops below 241 psi (1660 kPa) the fan will shut OFF. The fans will automatically shut OFF after 2 min. regardless of coolant temperature.

Circuit Testing

Ignition OFF, disconnect the harness connector at the Fan Control Module.

Fig. Cooling system connector end view

Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit and ground.

If greater than 1.0 ohm, test the ground circuit for an open/high resistance.

Ignition ON, test for B+ between the battery positive voltage circuit and ground.

If less than B+, test the battery positive voltage circuit for a short to ground or an open/high resistance.

If the COOLFAN fuse is open, test battery positive voltage circuit for a short to ground.

With a digital multi-meter, test for B+ between the B+ circuit terminal 3 and the control circuit terminal 6.

If less than B+, test the control circuit for and open/high resistance.